MCJIT: Add faux remote target execution to lli for the MCJIT.

Simulate a remote target address space by allocating a seperate chunk of
memory for the target and re-mapping section addresses to that prior to
execution. Later we'll want to have a truly remote process, but for now
this gets us closer to being able to test the remote target
functionality outside LLDB.

rdar://12157052

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163216 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 498 insertions, 29 deletions

diff --git a/tools/lli/RecordingMemoryManager.cpp b/tools/lli/RecordingMemoryManager.cpp
new file mode 100644
index 0000000000..9e1cff5527
--- /dev/null
+++ b/tools/lli/RecordingMemoryManager.cpp
@@ -0,0 +1,87 @@
+//===- RecordingMemoryManager.cpp - Recording memory manager --------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This memory manager allocates local storage and keeps a record of each
+// allocation. Iterators are provided for all data and code allocations.
+//
+//===----------------------------------------------------------------------===//
+
+#include "RecordingMemoryManager.h"
+using namespace llvm;
+
+uint8_t *RecordingMemoryManager::
+allocateCodeSection(uintptr_t Size, unsigned Alignment, unsigned SectionID) {
+  // The recording memory manager is just a local copy of the remote target.
+  // The alignment requirement is just stored here for later use. Regular
+  // heap storage is sufficient here.
+  void *Addr = malloc(Size);
+  assert(Addr && "malloc() failure!");
+  sys::MemoryBlock Block(Addr, Size);
+  AllocatedCodeMem.push_back(Allocation(Block, Alignment));
+  return (uint8_t*)Addr;
+}
+
+uint8_t *RecordingMemoryManager::
+allocateDataSection(uintptr_t Size, unsigned Alignment, unsigned SectionID) {
+  // The recording memory manager is just a local copy of the remote target.
+  // The alignment requirement is just stored here for later use. Regular
+  // heap storage is sufficient here.
+  void *Addr = malloc(Size);
+  assert(Addr && "malloc() failure!");
+  sys::MemoryBlock Block(Addr, Size);
+  AllocatedDataMem.push_back(Allocation(Block, Alignment));
+  return (uint8_t*)Addr;
+}
+void RecordingMemoryManager::setMemoryWritable() { llvm_unreachable("Unexpected!"); }
+void RecordingMemoryManager::setMemoryExecutable() { llvm_unreachable("Unexpected!"); }
+void RecordingMemoryManager::setPoisonMemory(bool poison) { llvm_unreachable("Unexpected!"); }
+void RecordingMemoryManager::AllocateGOT() { llvm_unreachable("Unexpected!"); }
+uint8_t *RecordingMemoryManager::getGOTBase() const {
+  llvm_unreachable("Unexpected!");
+  return 0;
+}
+uint8_t *RecordingMemoryManager::startFunctionBody(const Function *F, uintptr_t &ActualSize){
+  llvm_unreachable("Unexpected!");
+  return 0;
+}
+uint8_t *RecordingMemoryManager::allocateStub(const GlobalValue* F, unsigned StubSize,
+                                              unsigned Alignment) {
+  llvm_unreachable("Unexpected!");
+  return 0;
+}
+void RecordingMemoryManager::endFunctionBody(const Function *F, uint8_t *FunctionStart,
+                                             uint8_t *FunctionEnd) {
+  llvm_unreachable("Unexpected!");
+}
+uint8_t *RecordingMemoryManager::allocateSpace(intptr_t Size, unsigned Alignment) {
+  llvm_unreachable("Unexpected!");
+  return 0;
+}
+uint8_t *RecordingMemoryManager::allocateGlobal(uintptr_t Size, unsigned Alignment) {
+  llvm_unreachable("Unexpected!");
+  return 0;
+}
+void RecordingMemoryManager::deallocateFunctionBody(void *Body) {
+  llvm_unreachable("Unexpected!");
+}
+uint8_t* RecordingMemoryManager::startExceptionTable(const Function* F, uintptr_t &ActualSize) {
+  llvm_unreachable("Unexpected!");
+  return 0;
+}
+void RecordingMemoryManager::endExceptionTable(const Function *F, uint8_t *TableStart,
+                                               uint8_t *TableEnd, uint8_t* FrameRegister) {
+  llvm_unreachable("Unexpected!");
+}
+void RecordingMemoryManager::deallocateExceptionTable(void *ET) {
+  llvm_unreachable("Unexpected!");
+}
+void *RecordingMemoryManager::getPointerToNamedFunction(const std::string &Name,
+                                                        bool AbortOnFailure) {
+  return NULL;
+}
diff --git a/tools/lli/RecordingMemoryManager.h b/tools/lli/RecordingMemoryManager.h
new file mode 100644
index 0000000000..1590235a79
--- /dev/null
+++ b/tools/lli/RecordingMemoryManager.h
@@ -0,0 +1,78 @@
+//===- RecordingMemoryManager.h - LLI MCJIT recording memory manager ------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This memory manager allocates local storage and keeps a record of each
+// allocation. Iterators are provided for all data and code allocations.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef RECORDINGMEMORYMANAGER_H
+#define RECORDINGMEMORYMANAGER_H
+
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ExecutionEngine/JITMemoryManager.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/Memory.h"
+#include <utility>
+
+namespace llvm {
+
+class RecordingMemoryManager : public JITMemoryManager {
+public:
+  typedef std::pair<sys::MemoryBlock, unsigned> Allocation;
+
+private:
+  SmallVector<Allocation, 16> AllocatedDataMem;
+  SmallVector<Allocation, 16> AllocatedCodeMem;
+
+public:
+  RecordingMemoryManager() {}
+  virtual ~RecordingMemoryManager() {}
+
+  typedef SmallVectorImpl<Allocation>::const_iterator const_data_iterator;
+  typedef SmallVectorImpl<Allocation>::const_iterator const_code_iterator;
+
+  const_data_iterator data_begin() const { return AllocatedDataMem.begin(); }
+  const_data_iterator   data_end() const { return AllocatedDataMem.end(); }
+  const_code_iterator code_begin() const { return AllocatedCodeMem.begin(); }
+  const_code_iterator   code_end() const { return AllocatedCodeMem.end(); }
+
+  uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment,
+                                       unsigned SectionID);
+
+  uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment,
+                                       unsigned SectionID);
+
+  void *getPointerToNamedFunction(const std::string &Name,
+                                  bool AbortOnFailure = true);
+  // The following obsolete JITMemoryManager calls are stubbed out for
+  // this model.
+  void setMemoryWritable();
+  void setMemoryExecutable();
+  void setPoisonMemory(bool poison);
+  void AllocateGOT();
+  uint8_t *getGOTBase() const;
+  uint8_t *startFunctionBody(const Function *F, uintptr_t &ActualSize);
+  uint8_t *allocateStub(const GlobalValue* F, unsigned StubSize,
+                        unsigned Alignment);
+  void endFunctionBody(const Function *F, uint8_t *FunctionStart,
+                       uint8_t *FunctionEnd);
+  uint8_t *allocateSpace(intptr_t Size, unsigned Alignment);
+  uint8_t *allocateGlobal(uintptr_t Size, unsigned Alignment);
+  void deallocateFunctionBody(void *Body);
+  uint8_t* startExceptionTable(const Function* F, uintptr_t &ActualSize);
+  void endExceptionTable(const Function *F, uint8_t *TableStart,
+                         uint8_t *TableEnd, uint8_t* FrameRegister);
+  void deallocateExceptionTable(void *ET);
+
+};
+
+} // end namespace llvm
+
+#endif
diff --git a/tools/lli/RemoteTarget.cpp b/tools/lli/RemoteTarget.cpp
new file mode 100644
index 0000000000..2ab098b2ef
--- /dev/null
+++ b/tools/lli/RemoteTarget.cpp
@@ -0,0 +1,61 @@
+//===- RemoteTarget.cpp - LLVM Remote process JIT execution --------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Implementation of the RemoteTarget class which executes JITed code in a
+// separate address range from where it was built.
+//
+//===----------------------------------------------------------------------===//
+
+#include "RemoteTarget.h"
+#include <llvm/ADT/StringRef.h>
+#include <llvm/Support/Memory.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string>
+using namespace llvm;
+
+bool RemoteTarget::allocateSpace(size_t Size, unsigned Alignment,
+                                 uint64_t &Address) {
+  sys::MemoryBlock *Prev = Allocations.size() ? &Allocations.back() : NULL;
+  sys::MemoryBlock Mem = sys::Memory::AllocateRWX(Size, Prev, &ErrorMsg);
+  if (Mem.base() == NULL)
+    return true;
+  if ((uintptr_t)Mem.base() % Alignment) {
+    ErrorMsg = "unable to allocate sufficiently aligned memory";
+    return true;
+  }
+  Address = reinterpret_cast<uint64_t>(Mem.base());
+  return false;
+}
+
+bool RemoteTarget::loadData(uint64_t Address, const void *Data, size_t Size) {
+  memcpy ((void*)Address, Data, Size);
+  sys::MemoryBlock Mem((void*)Address, Size);
+  sys::Memory::setExecutable(Mem, &ErrorMsg);
+  return false;
+}
+
+bool RemoteTarget::loadCode(uint64_t Address, const void *Data, size_t Size) {
+  memcpy ((void*)Address, Data, Size);
+  return false;
+}
+
+bool RemoteTarget::executeCode(uint64_t Address, int &RetVal) {
+  int (*fn)(void) = (int(*)(void))Address;
+  RetVal = fn();
+  return false;
+}
+
+void RemoteTarget::create() {
+}
+
+void RemoteTarget::stop() {
+  for (unsigned i = 0, e = Allocations.size(); i != e; ++i)
+    sys::Memory::ReleaseRWX(Allocations[i]);
+}
diff --git a/tools/lli/RemoteTarget.h b/tools/lli/RemoteTarget.h
new file mode 100644
index 0000000000..f4dcf42ebe
--- /dev/null
+++ b/tools/lli/RemoteTarget.h
@@ -0,0 +1,101 @@
+//===- RemoteTarget.h - LLVM Remote process JIT execution ----------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Definition of the RemoteTarget class which executes JITed code in a
+// separate address range from where it was built.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef REMOTEPROCESS_H
+#define REMOTEPROCESS_H
+
+#include <llvm/ADT/StringRef.h>
+#include <llvm/ADT/SmallVector.h>
+#include <llvm/Support/Memory.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string>
+
+namespace llvm {
+
+class RemoteTarget {
+  std::string ErrorMsg;
+  bool IsRunning;
+
+  SmallVector<sys::MemoryBlock, 16> Allocations;
+
+public:
+  StringRef getErrorMsg() const { return ErrorMsg; }
+
+  /// Allocate space in the remote target address space.
+  ///
+  /// @param      Size      Amount of space, in bytes, to allocate.
+  /// @param      Alignment Required minimum alignment for allocated space.
+  /// @param[out] Address   Remote address of the allocated memory.
+  ///
+  /// @returns False on success. On failure, ErrorMsg is updated with
+  ///          descriptive text of the encountered error.
+  bool allocateSpace(size_t Size, unsigned Alignment, uint64_t &Address);
+
+  /// Load data into the target address space.
+  ///
+  /// @param      Address   Destination address in the target process.
+  /// @param      Data      Source address in the host process.
+  /// @param      Size      Number of bytes to copy.
+  ///
+  /// @returns False on success. On failure, ErrorMsg is updated with
+  ///          descriptive text of the encountered error.
+  bool loadData(uint64_t Address, const void *Data, size_t Size);
+
+  /// Load code into the target address space and prepare it for execution.
+  ///
+  /// @param      Address   Destination address in the target process.
+  /// @param      Data      Source address in the host process.
+  /// @param      Size      Number of bytes to copy.
+  ///
+  /// @returns False on success. On failure, ErrorMsg is updated with
+  ///          descriptive text of the encountered error.
+  bool loadCode(uint64_t Address, const void *Data, size_t Size);
+
+  /// Execute code in the target process. The called function is required
+  /// to be of signature int "(*)(void)".
+  ///
+  /// @param      Address   Address of the loaded function in the target
+  ///                       process.
+  /// @param[out] RetVal    The integer return value of the called function.
+  ///
+  /// @returns False on success. On failure, ErrorMsg is updated with
+  ///          descriptive text of the encountered error.
+  bool executeCode(uint64_t Address, int &RetVal);
+
+  /// Minimum alignment for memory permissions. Used to seperate code and
+  /// data regions to make sure data doesn't get marked as code or vice
+  /// versa.
+  ///
+  /// @returns Page alignment return value. Default of 4k.
+  unsigned getPageAlignment() { return 4096; }
+
+  /// Start the remote process.
+  void create();
+
+  /// Terminate the remote process.
+  void stop();
+
+  RemoteTarget() : ErrorMsg(""), IsRunning(false) {}
+  ~RemoteTarget() { if (IsRunning) stop(); }
+
+private:
+  // Main processing function for the remote target process. Command messages
+  // are received on file descriptor CmdFD and responses come back on OutFD.
+  static void doRemoteTargeting(int CmdFD, int OutFD);
+};
+
+} // end namespace llvm
+
+#endif
diff --git a/tools/lli/lli.cpp b/tools/lli/lli.cpp
index 3a3f4c7cdd..4004b6c4d4 100644
--- a/tools/lli/lli.cpp
+++ b/tools/lli/lli.cpp
@@ -13,6 +13,9 @@
 //
 //===----------------------------------------------------------------------===//
 
+#define DEBUG_TYPE "lli"
+#include "RecordingMemoryManager.h"
+#include "RemoteTarget.h"
 #include "llvm/LLVMContext.h"
 #include "llvm/Module.h"
 #include "llvm/Type.h"
@@ -32,9 +35,11 @@
 #include "llvm/Support/PluginLoader.h"
 #include "llvm/Support/PrettyStackTrace.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/Format.h"
 #include "llvm/Support/Process.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/Support/TargetSelect.h"
+#include "llvm/Support/Debug.h"
 #include "llvm/Support/DynamicLibrary.h"
 #include "llvm/Support/Memory.h"
 #include <cerrno>
@@ -73,6 +78,13 @@ namespace {
     "use-mcjit", cl::desc("Enable use of the MC-based JIT (if available)"),
     cl::init(false));
 
+  // The MCJIT supports building for a target address space separate from
+  // the JIT compilation process. Use a forked process and a copying
+  // memory manager with IPC to execute using this functionality.
+  cl::opt<bool> RemoteMCJIT("remote-mcjit",
+    cl::desc("Execute MCJIT'ed code in a separate process."),
+    cl::init(false));
+
   // Determine optimization level.
   cl::opt<char>
   OptLevel("O",
@@ -372,6 +384,79 @@ LLIMCJITMemoryManager::~LLIMCJITMemoryManager() {
     free(AllocatedDataMem[i].base());
 }
 
+
+void layoutRemoteTargetMemory(RemoteTarget *T, RecordingMemoryManager *JMM) {
+  // Lay out our sections in order, with all the code sections first, then
+  // all the data sections.
+  uint64_t CurOffset = 0;
+  unsigned MaxAlign = T->getPageAlignment();
+  SmallVector<std::pair<const void*, uint64_t>, 16> Offsets;
+  SmallVector<unsigned, 16> Sizes;
+  for (RecordingMemoryManager::const_code_iterator I = JMM->code_begin(),
+                                                   E = JMM->code_end();
+       I != E; ++I) {
+    DEBUG(dbgs() << "code region: size " << I->first.size()
+                 << ", alignment " << I->second << "\n");
+    // Align the current offset up to whatever is needed for the next
+    // section.
+    unsigned Align = I->second;
+    CurOffset = (CurOffset + Align - 1) / Align * Align;
+    // Save off the address of the new section and allocate its space.
+    Offsets.push_back(std::pair<const void*,uint64_t>(I->first.base(), CurOffset));
+    Sizes.push_back(I->first.size());
+    CurOffset += I->first.size();
+  }
+  // Adjust to keep code and data aligned on seperate pages.
+  CurOffset = (CurOffset + MaxAlign - 1) / MaxAlign * MaxAlign;
+  unsigned FirstDataIndex = Offsets.size();
+  for (RecordingMemoryManager::const_data_iterator I = JMM->data_begin(),
+                                                   E = JMM->data_end();
+       I != E; ++I) {
+    DEBUG(dbgs() << "data region: size " << I->first.size()
+                 << ", alignment " << I->second << "\n");
+    // Align the current offset up to whatever is needed for the next
+    // section.
+    unsigned Align = I->second;
+    CurOffset = (CurOffset + Align - 1) / Align * Align;
+    // Save off the address of the new section and allocate its space.
+    Offsets.push_back(std::pair<const void*,uint64_t>(I->first.base(), CurOffset));
+    Sizes.push_back(I->first.size());
+    CurOffset += I->first.size();
+  }
+
+  // Allocate space in the remote target.
+  uint64_t RemoteAddr;
+  if (T->allocateSpace(CurOffset, MaxAlign, RemoteAddr))
+    report_fatal_error(T->getErrorMsg());
+  // Map the section addresses so relocations will get updated in the local
+  // copies of the sections.
+  for (unsigned i = 0, e = Offsets.size(); i != e; ++i) {
+    uint64_t Addr = RemoteAddr + Offsets[i].second;
+    EE->mapSectionAddress(const_cast<void*>(Offsets[i].first), Addr);
+
+    DEBUG(dbgs() << "  Mapping local: " << Offsets[i].first
+                 << " to remote: " << format("%#018x", Addr) << "\n");
+
+  }
+  // Now load it all to the target.
+  for (unsigned i = 0, e = Offsets.size(); i != e; ++i) {
+    uint64_t Addr = RemoteAddr + Offsets[i].second;
+
+    if (i < FirstDataIndex) {
+      T->loadCode(Addr, Offsets[i].first, Sizes[i]);
+
+      DEBUG(dbgs() << "  loading code: " << Offsets[i].first
+            << " to remote: " << format("%#018x", Addr) << "\n");
+    } else {
+      T->loadData(Addr, Offsets[i].first, Sizes[i]);
+
+      DEBUG(dbgs() << "  loading data: " << Offsets[i].first
+            << " to remote: " << format("%#018x", Addr) << "\n");
+    }
+
+  }
+}
+
 //===----------------------------------------------------------------------===//
 // main Driver function
 //
@@ -428,12 +513,19 @@ int main(int argc, char **argv, char * const *envp) {
     Mod->setTargetTriple(Triple::normalize(TargetTriple));
 
   // Enable MCJIT if desired.
-  LLIMCJITMemoryManager *JMM = 0;
+  JITMemoryManager *JMM = 0;
   if (UseMCJIT && !ForceInterpreter) {
     builder.setUseMCJIT(true);
-    JMM = new LLIMCJITMemoryManager();
+    if (RemoteMCJIT)
+      JMM = new RecordingMemoryManager();
+    else
+      JMM = new LLIMCJITMemoryManager();
     builder.setJITMemoryManager(JMM);
   } else {
+    if (RemoteMCJIT) {
+      errs() << "error: Remote process execution requires -use-mcjit\n";
+      exit(1);
+    }
     builder.setJITMemoryManager(ForceInterpreter ? 0 :
                                 JITMemoryManager::CreateDefaultMemManager());
   }
@@ -451,11 +543,14 @@ int main(int argc, char **argv, char * const *envp) {
   }
   builder.setOptLevel(OLvl);
 
-  TargetOptions Options;
-  Options.JITExceptionHandling = EnableJITExceptionHandling;
-  Options.JITEmitDebugInfo = EmitJitDebugInfo;
-  Options.JITEmitDebugInfoToDisk = EmitJitDebugInfoToDisk;
-  builder.setTargetOptions(Options);
+  // Remote target execution doesn't handle EH or debug registration.
+  if (!RemoteMCJIT) {
+    TargetOptions Options;
+    Options.JITExceptionHandling = EnableJITExceptionHandling;
+    Options.JITEmitDebugInfo = EmitJitDebugInfo;
+    Options.JITEmitDebugInfoToDisk = EmitJitDebugInfoToDisk;
+    builder.setTargetOptions(Options);
+  }
 
   EE = builder.create();
   if (!EE) {
@@ -473,6 +568,10 @@ int main(int argc, char **argv, char * const *envp) {
   EE->RegisterJITEventListener(
                 JITEventListener::createIntelJITEventListener());
 
+  if (!NoLazyCompilation && RemoteMCJIT) {
+    errs() << "warning: remote mcjit does not support lazy compilation\n";
+    NoLazyCompilation = true;
+  }
   EE->DisableLazyCompilation(NoLazyCompilation);
 
   // If the user specifically requested an argv[0] to pass into the program,
@@ -509,8 +608,13 @@ int main(int argc, char **argv, char * const *envp) {
   // Reset errno to zero on entry to main.
   errno = 0;
 
+  // Remote target MCJIT doesn't (yet) support static constructors. No reason
+  // it couldn't. This is a limitation of the LLI implemantation, not the
+  // MCJIT itself. FIXME.
+  //
   // Run static constructors.
-  EE->runStaticConstructorsDestructors(false);
+  if (!RemoteMCJIT)
+    EE->runStaticConstructorsDestructors(false);
 
   if (NoLazyCompilation) {
     for (Module::iterator I = Mod->begin(), E = Mod->end(); I != E; ++I) {
@@ -520,28 +624,66 @@ int main(int argc, char **argv, char * const *envp) {
     }
   }
 
-  // Clear instruction cache before code will be executed.
-  if (JMM)
-    JMM->invalidateInstructionCache();
-
-  // Run main.
-  int Result = EE->runFunctionAsMain(EntryFn, InputArgv, envp);
+  int Result;
+  if (RemoteMCJIT) {
+    RecordingMemoryManager *MM = static_cast<RecordingMemoryManager*>(JMM);
+    // Everything is prepared now, so lay out our program for the target
+    // address space, assign the section addresses to resolve any relocations,
+    // and send it to the target.
+    RemoteTarget Target;
+    Target.create();
+
+    // Ask for a pointer to the entry function. This triggers the actual
+    // compilation.
+    (void)EE->getPointerToFunction(EntryFn);
+
+    // Enough has been compiled to execute the entry function now, so
+    // layout the target memory.
+    layoutRemoteTargetMemory(&Target, MM);
+
+    // Since we're executing in a (at least simulated) remote address space,
+    // we can't use the ExecutionEngine::runFunctionAsMain(). We have to
+    // grab the function address directly here and tell the remote target
+    // to execute the function.
+    // FIXME: argv and envp handling.
+    uint64_t Entry = (uint64_t)EE->getPointerToFunction(EntryFn);
+
+    DEBUG(dbgs() << "Executing '" << EntryFn->getName() << "' at "
+                 << format("%#18x", Entry) << "\n");
+
+    if (Target.executeCode(Entry, Result))
+      errs() << "ERROR: " << Target.getErrorMsg() << "\n";
+
+    Target.stop();
+  } else {
+    // Clear instruction cache before code will be executed.
+    if (JMM)
+      static_cast<LLIMCJITMemoryManager*>(JMM)->invalidateInstructionCache();
 
-  // Run static destructors.
-  EE->runStaticConstructorsDestructors(true);
+    // Run main.
+    Result = EE->runFunctionAsMain(EntryFn, InputArgv, envp);
+  }
 
-  // If the program didn't call exit explicitly, we should call it now.
-  // This ensures that any atexit handlers get called correctly.
-  if (Function *ExitF = dyn_cast<Function>(Exit)) {
-    std::vector<GenericValue> Args;
-    GenericValue ResultGV;
-    ResultGV.IntVal = APInt(32, Result);
-    Args.push_back(ResultGV);
-    EE->runFunction(ExitF, Args);
-    errs() << "ERROR: exit(" << Result << ") returned!\n";
-    abort();
-  } else {
-    errs() << "ERROR: exit defined with wrong prototype!\n";
-    abort();
+  // Like static constructors, the remote target MCJIT support doesn't handle
+  // this yet. It could. FIXME.
+  if (!RemoteMCJIT) {
+    // Run static destructors.
+    EE->runStaticConstructorsDestructors(true);
+
+    // If the program didn't call exit explicitly, we should call it now.
+    // This ensures that any atexit handlers get called correctly.
+    if (Function *ExitF = dyn_cast<Function>(Exit)) {
+      std::vector<GenericValue> Args;
+      GenericValue ResultGV;
+      ResultGV.IntVal = APInt(32, Result);
+      Args.push_back(ResultGV);
+      EE->runFunction(ExitF, Args);
+      errs() << "ERROR: exit(" << Result << ") returned!\n";
+      abort();
+    } else {
+      errs() << "ERROR: exit defined with wrong prototype!\n";
+      abort();
+    }
   }
+  return Result;
 }